The present invention generally relates to a tool head for a dual punch tool such as a pneumatic punch. More particularly, the invention relates to a tool head having two different punch pins operably provided therein.
Pneumatic punches are small hand-held tools used for machining. As shown in FIGS. 5 and 6, a conventional pneumatic punch 50 typically has a tool head 60 provided on a movable shaft 55, which is movable in an axial direction thereof. The tool head 60 comprises an L-shaped fixed seat 61 and an inverted L-shaped movable seat 65 mated with the fixed seat 61. The fixed seat 61 is fixedly mounted on a main body 50a of the pneumatic punch 50 and defines an aperture 610 therein to permit the movable shaft 55 to extend therethrough, and further defines a receiving recess or groove 62 to receive a punch pin 63 and an elastic element 64 provided around the punch pin 63. A side cover 70 securely mounted on a top opening 62a of the receiving recess 62 limits the lateral movement of the punch pin 63 and the elastic element 64. The movable seat 65 defines a screw hole 650 corresponding to the aperture 610 of the fixed seat 61 to be fixed to a threaded end of the moving shaft 55. The movable seat 65 also defines a discharging passage 66 corresponding to the punch pin 63. A transverse slot groove 67 is defined in the movable seat 65 and is substantially perpendicular to the discharging passage 66. The discharging passage 66 has two opposite openings 67a, 67b in communication with the transverse slot 67 respectively provided with a first guide cylinder 68 and a second guide cylinder 69.
In operation, and as shown in FIG. 6, when a sheet plate 72 is inserted for punching into the transverse groove 67, and between the first guide cylinder 68 and the second guide cylinder 69, the pneumatic punch 50 is actuated to retract the moving shaft 55. This action draws the movable seat 65 toward the fixed seat 61. Accordingly, the punch pin 63 is inserted through the second guide cylinder 69 into the first guide cylinder 68. A waste sheet 74 punched off the sheet plate 72 is discharged via the discharging passage 66.
However, the conventional pneumatic punch 50 only has one punch pin 63 provided to punch only one type or size of punched hole in a sheet plate, though other conventional devices are believed to also have a flange, or the like. If a work piece needs to be punched with two different hole sizes, for example, the punch pin 63 of the conventional tool head 60 of the pneumatic punch 50 must be changed or replaced frequently, or a second pneumatic size punch 50 with a different punch pin must be available.
Accordingly, it is an objective of the present invention to provide an improved tool head of a hole punching device that can punch two different sizes or types of holes in a work piece by repositioning a single tool head.
These and other objects, advantages and novel features of the present invention are discussed or will be apparent in the detailed description of the invention.
In keeping with one aspect of the present invention, a hand-held, hole punching device has a shaft, a main body with a device for axially moving the shaft in a reciprocating motion and a tool head connected to the shaft. The tool head includes a fixed portion on the main body for slidably engaging the shaft so that the fixed portion permits the shaft to slide axially relative to the fixed portion. The tool head also has a movable portion secured to the shaft so that the movable portion moves axially with the shaft. The movable portion and the fixed portion cooperatively define at least two hole punchers. Each hole puncher has a punch pin that is different from a punch pin of any other hole puncher on the tool head.
In another aspect of the present invention, the hole punching device also includes a fixed portion that is configured with a generally upright J-shaped formation and a movable portion that is configured with a generally inverted J-shaped formation. The portions are then disposed relative to each other so that the fixed portion impedes axial motion of the movable portion.
In yet another aspect of the present invention, the hole punching device further includes a fixed portion with an axially extending guide block and a movable portion with an axially extending guide slot configured and disposed for matingly engaging the guide block. The mating of the guide block with the guide slot at least prevents lateral movement of either the fixed or the movable portion relative to the corresponding other fixed or movable portion on the tool head.